Help! I have a 1990 Chevy silverado k1500 5.7L TBI with a manual trans. When I bought the truck I noticed the gas pedal was stiff which made it difficult to smoothy accelerate in 1st and 2nd gear. I have to apply more pressure than normal before the pedal even moves. Naturally I checked the trottle cable, and pedal assembly but everything checks out fine. When the truck is not running the pedal is smooth and soft, however when its running its stiff and choppy. When I try to very lightly rev the engine in neutral it just jumps up to 3500 RPM and VERY slowly returns to idle. the same thing happens when i take it out of gear, it revs up and slowly comes down to idling speed. Ive tried everything from cleaning up the throttle body to spraying oil down the throttle cable casing, but the pedal is only stiff and choppy while its running. Could a throttle positioning sensor have anything to do with it?Its hard to explain without actually driving it but it would be nice to be able to slowly and smoothly accelerate instead lurching forward and having to ride out the clutch because of the stiff/inconsistant throttle response. Anyone have any ideas what to do about this or possibly ran into this issue?